Memory devices are typically provided as internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including random-access memory (RAM), read only memory (ROM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), and flash memory.
Flash memory devices have developed into a popular source of non-volatile memory for a wide range of electronic applications. Non-volatile memory is memory that can retain its data values for some extended period without the application of power. Flash memory devices typically use a one-transistor memory cell that allows for high memory densities, high reliability, and low power consumption. Changes in threshold voltage of the cells, through programming of charge storage or trapping layers or other physical phenomena, determine the data value of each cell. By defining two or more ranges of threshold voltages to correspond to individual data values, one or more bits of information may be stored on each cell. Common uses for flash memory and other non-volatile memory include personal computers, personal digital assistants (PDAs), digital cameras, digital media players, digital recorders, games, appliances, vehicles, wireless devices, mobile telephones and removable memory modules, and the uses for non-volatile memory continue to expand.
Flash memory typically utilizes one of two basic architectures known as NOR flash and NAND flash. The designation is derived from the logic used to read the devices. In NOR flash architecture, a column of memory cells are coupled in parallel with each memory cell coupled to a bit line. In NAND flash architecture, a column of memory cells are coupled in series with only the first memory cell of the column coupled to a bit line.
One common type of flash memory is a nitride read only memory (NROM), sometimes referred to as silicon-oxide-nitride-oxide-silicon (SONOS) memory. Such devices generally include silicon nitride (Si3N4) as a charge-trapping node, although other dielectric materials may be utilized. By accumulating charge in, or discharging, the charge-trapping node within a memory cell, the threshold voltage of that memory cell may be altered. As memory cells become smaller, it generally becomes more difficult to accumulate sufficient charge to readily distinguish differing data states, and charge retention of the charge-trapping node becomes increasingly critical.
For the reasons stated above, and for other reasons that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternative charge-trapping materials for use in non-volatile memory devices.